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<title> BALSAC Version 2.15 Manual, Section 5.2</title>
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<h1>5.2.  DISPLAYING CRYSTAL SURFACES</h1>

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In studies of single crystal surfaces Miller indices are usually defined such
that the lattice plane normal points from the crystal into vacuum. Thus,
lattice plane stacking towards the bulk proceeds opposite to the surface
normal direction. In contrast, BALSAC builds lattice sections such that plane
stacking proceeds along the normal direction. As a consequence, for view
angles THETA &lt; 90 a section of N layers representing the surface and N-1
underlying layers is visualized in the layer by layer mode such that the Nth
underlayer is shown first and the surface layer last.
 
The above layer building sequence can be reversed visually by a simple trick:
To display a surface with Miller indices (h k l) use values (-h -k -l), see
Sec. <a href="./balm.60.html">6.2.3</a>, view angles THETA &gt; 90, and a screen rotation ROT = 180 degrees,
see Sec. <a href="./balm.63.html">6.2.6</a>. Note, however, that in layer-by-layer display mode lattice
plane stacking away from the viewer for THETA &gt; 90 degrees may lead to
erroneous pictures since the hidden surface algorithm can fail.
 
 
 
 

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